Combination fluidized solids process for producing fuels and chemicals



J. F. MOSER, JR COMBINATION FLUIDIZED SOLIDS PROCESS FOR Feb. 17, 1959PRODUCING FUELS AND CHEMICALS Filed Dec. 8, 1954 FUELS PRODUCT QUENCHRECOVERY BURNER VESSEL R E E0 0 U U. 7 Hr F G W Al mm flnunnnn U 2 L F Bm f .l 9 m W m 6 A E W v E w m m. mm w T s m o .P HHH R W i Q P G E A s5 m& B P S N ME v P A EK lS RE R HO V T CC 2 S S W #T. C M 6 v U 2 E4, KE mo w 1 J W F M r Ts (W A v v v LG W0 3 3 2 Inventor Attorney COMBINATION FLUIDIZED SOLIDS PROCESS FOR- PRQDUCING FUELS AND CHEMICALS Jann-nastier Moser, Jr'.-, Baton Rouge, La, assignor to Esfso kesearch andEngineering Company, a corporation -of Delaware"- Application December8, 1954, Serial No. 473,775

3 Claims; (Cl. 20220) to the-present invention comprises heavy highboiling oilscontaining catalyst contaminants or refractory constit'uentsth'at render other methods of upgrading unattractive.- Suchmaterials as petroleum residue, coal tars,-shale' oils,- asphalts,extracts, etc., are illustrative of suitable'charging stocksr Accordingto this invention, a heavy oil, e. g-., avacuum-residuum, iscontacted-in a fluidized solidsfuelscoking zone with particulatesolids-maintained at a coking temperature in therange of 850 to 1200"F."The oil, upon contact with the solids, undergoes vaporization'andpyrolysis evolving relatively lighter hydrocarbon vaporsanddepositingresidue on the solids. The time of'contact-'is-regulated-so that only'a part of the feed isconverted to vapors.The'solids along Withthe adhering remaining'portion'of the heavyoil arethen withdrawnfrom the coking zone and mixed With additionalhightemperature particulate solids in a chemicals coking zone,prefcrably 'a transfer line zone, whereby the resulting mixture hasatemperature in the range of 1200" 'to 1600" This-results inthe'conversion of the-remaining portions of- 'the feed tolightunsaturates and similar-compounds suitable as chemical raw materials;After having entrained solids removed, the vaporousconversion productsfr'om-th'e fuels and'chemicals coking zones areseparately recovered asproducts." The solids separated fromthe chemical cokingzone efliuentarestripped and amajor portionof thestripped solids is circulated tothefuels coking 'zone to maintain the: coking temperature. The;remainder; is scirculated through aheating'. zone wherein they areheated, preferably: by partial combustion, to a temperature-100 to 900F. above the temperature in the chemicals coking zone; Thfereheatedsolids are then returned to-the chemicalscoking zone.

It canbe seen that-this fluidized solids coking system provides, inessence, for the production of-fuelsat high solids-oil ratios or: withlow solids holdingtimes inta fuels coking zonetso that the oilundergoing treatmentls not completely converted or cracked. Theunconverted atentt) 2,874,093 Patented Feb. 17, 1959 feed 'on the solidsis then 'completely'converted in-a-high" temperature chemicals cokingzone; The process uti lizesa single inventory of circulating solidsyand'all'of the heat for the process is supplied by a common :heat ingsystem. The heating system: comprises, preferably, a burner wherein aportionof the carbon-containingpar ticles are partially combusted.

It is to be appreciated that-this'invention diverts'to fuels productionthe lighter, high hydrogen containing, fraction of thefeed' anddivertsthe heavier, low hydrogencontaining, components to chemicalsproduction. The present process isiparticularly adapted to handling along residuum, i. e., a-residuum containing a substantial pro-- portionof constituents boiling below about 900 F; The

I fuels cokingzone is utilized to secure vaporization of the' lighterconstituents of along residuum, and the-chemicals" coking zone isutilized to completely convert the'heavy low value ends of the residuum.The ease of controllingthe fraction converted" to fuels in the fuels"coking-"zone results in a very flexible process;

The heat transferring particulate solids used ilfjtll" practice of thisinvention comprise any finely divided,- substantially' catalyticallyinert, refractory solid such as pumiceQkieselg'uhr, spent catalyst;sand, metal andfre fractory jbed's, etc. Particulate coke produced bytheprocess is the preferred contactsolidl As this is 'aflfiuidized'solidsprocess, the solids have, preferably, a size in-the range 0f740-500microns, although in some instances-the solids may varyconsiderablybeyond these limits,-e.*g., from 0 to 1000 micronsby'screen-analysis:

It-"is' an object of this-invention to devise a combine tion'fuels'andchemicals coking process whichutili'zesa single-inventory ofcirculatingcoke and a common coke heating system;

The drawing," attached to. and-forming aparhof this specification, willserve-to illustrate one preferredem' bodimentofthis invention."Thisfdrawing is for the purpose of illustration onlyand the invention isnot to be limited thereto.

In brief compass, theobjects of'this'invention are .attained in thefollowing'mannerz A charging'stockis con .t'a'cted in a fuels cokingzone .withxafiuidized bed of high temperature particulate solids;preferably, finely divided coke. A relatively' low solids residence timeis maintained in thecoking zone whereby only a portion of the chargingstock is vaporizedand converted to gasiformprod ucts. Solidsalongwith'adhering unconverted portions .ofthe charging stockare'removed from the fuels coking 'zone and transferred to'a chemicalscoking zone wherein Referring now to the attached drawing, the majoritems of equipment shown are a fluid bed fuels coker 10, a transfer linechemicals coker 20 and a fluid bed burner vessel 30. The feed to theprocess, e. g., a vacuum re siduum, which may be suitably preheated toreduce the heat load of the system, is injected into fuels coker 10 vialine 1. The injected oil is admitted to the vessel at a multiplicity ofpoints and an atomizing gas may be used to suitably disperse the oil onthe fluidized solids.

The fuels coker 10 has maintained in it a fluid bed of particulate cokein a manner well known by the art. The fuels coking temperature may varyfrom about 850 to 1200 F. Lower temperatures below 1,000 F. are usedwhen heavy distillates suitable as catalytic cracking feed stock aredesired and somewhat higher temperatures above 1,000 F. are used whenlighter distillates, e. g., naphthas are desired as the primaryproducts. An inert fluidizing gas, preferably steam, is supplied to thebase of vessel 10 by line 2. Gas rates are adjusted to maintainfluidization velocities in the range of about 0.2 to ft./ sec.

A high solids to oil ratio, or conversely a low solids holding time, isutilized in the fuels coker such that only a portion of the injectedfeed is vaporized and converted. The amount of the feed converted inthis zone is controlled primarily by the solids to oil ratio, but thecoking temperature, fluidization gas rate, etc., may also be regulatedto control the conversion. Generally, depending upon the nature of thefeed, it is desired to convert approximately 30 to 80% of the feed inthis zone to the products boiling below 1015 F.

The conversion products pass upwardly through the coking reactor tocyclone system 3 wherein entrained solids are removed from the vaporsand returned to the fluid bed. This cyclone system may be external ofreactor 10. The vapors are then separated by conventional means, e. g.,fractionation, to obtain the desired liquid distillate products. Asillustrated, a superposed scrubber 4 is used to quench and remove fromthe vapors the heavy high boiling ends. The heavy ends condensed fromthe vapors by this scrubbing are conveniently recycled via line 5 to thecoker to be retreated therein. A portion of these heavy ends are cooledin heat exchanger 6 and transferred to the top of scrubber 4 by line 7to serve as the quench oil. The initial boiling point of the heavy endscondensed in this arrangement is preferably in the range of 950 to 1150"F. The quenched vapors are removed from the scrubber 4 by line 8 and aretransferred to further conventional processing, not shown. Solids alongwith the unconverted portions of the feed are transferred via line 9 tothe chemicals coking zone 20. At the inlet of the chemicals coking zone,the wet solids are met with additional amounts of high temperaturesolids supplied by line 22, suflicient to raise the temperature of themixture above 1200 F. The transfer line chemicals coker is preferably avertically disposed, narrowly confined elongated conduit which may besuitably lined with refractory materials. A lift gas, preferably steam,although other gases such as light hydrocarbon gases may be used, isadmitted to the base of the chemicals coker by line 11 in amountssuflicient to carry the suspension through the chemicals coker atvelocities above 5 ft./sec.

At this high temperature, the liquid residue on the solids is rapidlyconverted to light unsaturates and similar compounds. To avoid unduethermal degradation of the conversion products, conversion times areheld at a minimum. It is preferred to maintain the average vaporresidence time of the conversion products before quenching in the rangeof 0.1 to 1.0 second. Stated somewhat differently, C conversions, on acoke free basis, of the liquid residue transferred to the chemicalscoker on the solids range from about 20 to 50 Wt. percent. The solids inpassing through the transfer line reactor are substantially completelydried with the carbonaceous residue deposited thereon forming coke whichbecomes a part of the solids. The effluent from the chemicals coker 20is rapidly separated in a cyclonic separator 12. The conversion productsare removed from separator by line 13. Preferably these products arequenched by a quench medium supplied by line 14 to below crackingtemperatures, as they issue from the cyclonic separator. The quenchmedium used is preferably a heavy hydrocarbon oil and may be composed ofthe heavy ends removed in scrubber 4. The quenched products in line 13are then sent to conventional processing equipment to recover thedesired chemicals and hydrocarbon fractions. Crystallization,fractionation, absorption, adsorption, etc., processes may be used toeffect the desired separation.

The solids removed by separator 12 are transferred by line 15 to astripping vessel wherein occluded hydrocarbons are removed from thesolids. A stripping gas, e. g., steam, is admitted to the base of thestripping vessel 16 by line 17 in amounts sufiicient to fluidize thesolids therein. The gases are recovered overhead from the strippingvessel and transferred to the dilute solids phase in the fuels coker 10by line 18. A major portion of the solids in the stripping vessel 16 aretransferred by line 19 to the fuels coker to supply heat thereto. Acooler, steam generator or heat exchanger 28, is preferably used topartially cool the solids circulated to the fuels coker. This givesgreater flexibility to the process in that the chemicals coker can beoperated at higher temperatures and permits a higher solids/oil ratio tobe used in the fuels coker without exceeding temperature limitations.Conveniently, steam can be generated in cooler 28 for use withintheprocess.

The remainder of the solids in vessel 16 are transferred by line 21 tothe burner vessel to be reheated. A lift gas, e. g., steam or air, issupplied to the contents of line 21 by line 23 to aid in the transfer ofthe solids to the burner vessel 30. The method of circulating thecontact solids used in the method of the present invention forms no partof this invention. Reference is made to co-pending application byWhiteley and Molstedt, Serial No. 439,702, to illustrate one method ofcirculating solids applicable to the present invention.

The means of supplying heat to the process also forms no part of thepresent invention. As shown, a fluid bed burner vessel is used topartially combust the carboncontaining solids transferred thereto. Airor other free oxygen-containing gas is admitted to the base of theburner vessel 30 by line 24 in amounts sulficient to fluid: ize thesolids therein and to support a partial combustion of the solids. Bythis means, the temperature of the solids is raised to a temperature 100to 900 F. above the chemicals coking temperature. Entrained solids areremoved from the flue gases by a cyclone separator system 25 located inthe dilute solids suspension phase above the fluid bed. The flue gasesare then vented by line 26. Normally an excess of coke is produced bythe process and this excess may be removed by line 27. The reheated cokeis transferred to the chemicals coker 20 by line 22 as previouslydescribed. A

Other means of supplying heated solid particles to the coking processcan, of course, be used. Besides the fluid bed burner illustrated,gravitating bed burners or transfer line burners may be used toaccomplish the partial combustion.. Other direct or indirect heatexchange means may be used if desired, such as shot heating systems,and, further, extraneous liquid or gaseous fuels may be preferentialycombusted in the burner to heat the solid particles.

The range of operating conditions applicable to the process illustratedin the drawing are summarized in Table I. Table I also presents aspecific example of operating conditions. Table H presents a specificexample of the products obtainable from the charging stock indicatedwhen a process is operated in accordance with the example of Table I.

Pressure vapor outlet, p. s. i. g. Coking temperature, F 1,015 F.Conversion, percent Temperature fresh solids, F Coke/oil ratio 1 t 20Average solids, residence time,

min. Fluidizing steam rate, wt. percent fresh feed. Bed density, lbs/C.F Transfer line chemicals coker:

Pressure outlet, s. i Avg. temperature, F Reheated coke/wet coke fromfuels coker ratio.

Temperature of reheated coke-.. 1,400 to 2,000---- 1,650.

Lift gas rate, 0. F./lb. wet coke 0.05 to 1 0.48.

Solids loading, lbs/O. F 1 to 20 4.

Coke throughput, lbs./Min./ft. 1,000 to 20,000.-. 10,000.

Solids velocity, ft./sec Above 6 20.

Average vapor residence time 0.1 to 10 1 before quenching, sec.

Ca conversion; percent 10 to 50 30. Fluid Bed Burner:

Temperature, F 1,400 to 2,000 1,650.

Bed density, lbs/O. F 25 to 60 40.

1 1,0l5 F. conversion is defined as 100 vol. percent fresh feed minusproducts boiling above 1,015 F. less coke.

2 conversion is defined as wt. percent of products having three or lesscarbon atoms divided by 100 wt. percent fresh feed, on a coke freebasis.

TABLE II Feed: South Louisiana long residuum 17.7 API gravity 4.8 wt.percent Conradson carbon 850 F. initial boiling point 0.1 wt. percentash 1.51 H/C atomic ratio Products: percent on fresh feed CHEMICALSCOKER FUELS (JOKER C wt. percent-.. 4.0 C Hydrocarbons vol. percent 1.5C 430 F., naptha vol. percent 10.5 430-10l5 F. gas oil vol. percent..-63.5 Gross coke make wt. percent 5.3

NOTE.AI1 1015 F.'+material from fuels coker efliuent is recycled toextinction.

Numerous variations of this invention will occur to those skilled in theart. It is to be appreciated that in certain applications either atransfer line reactor zone or a fluid bed fuels coking zone may be usedto accomplish either the initial low temperature conversion of the feedor the high temperature conversion of the remaining portions of thefeed. As indicated, however, a fluid bed operation is preferred for thefuels coking step and, because of the short contact times required inthe chemicals coking zone, a transfer line reactor zone is preferred forthis step. As an example of another variation, instead of stripping allof the solids in line 15, only the portion transferred to the burnervessel need be stripped.

Havingdescribed the invention, what is sought to be protected by LettersPatent, is succinctly set forth in the following claims.

What is claimed is:

l. A fluidized solids petroleum residua coking process for convertingcharge stock to fuels products and chemical unsaturates which comprises,in combination, coking a charging stock in a fluid bed fuels coking zonewhile maintaining a relatively low solids residence time whereby only aportion of the charging stock is converted to gasiform products,withdrawing solids and unconverted charging stock from the fluid bed,heating the withdrawn portion to a temperature above 1200 F. by addingadditional high temperature solids, passing the heated portion through atransfer line reactor to convert the remaining portions of said chargingstock to coke and light unsaturates while maintaining an average vaporresidence time of less than 10 seconds in said transfer line reactor,and separating and recovering the conversion products from each zonefrom the contact solids therein.

2. A hydrocarbon conversion process which comprises injecting a heavyhydrocarbon oil into a fuels coking zone containing a fluidized bed ofparticulate coke maintained at afuels coking temperature in the range of850 to 1200 F. to produce relatively lighter normally liquid conversionproducts while maintaining an average solids residence time in saidfuels coking zone within the range of l to 10 minutes whereby a 1015 F.l conversion in the range of 40 to is obtained, introducing heated cokeparticles into said fuels coking zone at a solids/ oil ratio in therange of l to 10, removing entrained solids from and recovering saidconversion products, withdrawing particulate coke along with the liquidresidue of said charging stock and heating the withdrawn coke to achemicals coking temperature in the range of 1200 to 1600 F. by mixingsaid withdrawn coke with 0.1 to 10 parts of additional coke per part ofwithdrawn coke having a temperature to 900 F. above the temperature ofsaid withdrawn coke, passing the resulting mixture through a transferline chemicals coke at velocities above 5 feet/see, whereby theremaining, heavier portion of said charging stock is converted to lighthydrocarbon gases and coke, the average vapor residence time beforequenching in said transfer line chemicals coker being under 10 secs.,separating coke from said light hydrocarbon gases and recovering thegases as product, stripping the coke so separated, partially cooling andreturning a major portion of the coke so stripped to said fuels cokingzone as said heated coke particles, circulating the remaining portion ofthe stripped coke to a heating zone wherein the temperature of the cokeis raised 100 to 900 F. above said chemicals coking temperature bypartial combustion, and returning the reheated coke to said chemicalscoking zone.

3. A combination fluid coking process for producing distillate fuels andchemical raw materials which comprises coking a petroleum residual oilin a fuels coker containing a fluid bed coking zone with a low solidsholding time whereby only a portion of the residual oil is converted andthe remainder is deposited on the solids, passing solids from said fluidbed coking zone to a transfor line chemicals coker, mixing additionalhot solids with the solids in the chemicals coker to raise thetemperature therein above 1200 F., passing the mixture through saidchemicals coker for a relatively short reaction period whereby lightunsaturates are produced, separating solids from the eflluent from saidchemicals coker, passing a major portion of the solids so separated tosaid fuels coking zone to supply heat thereto and circulating theremainder of the separated solids to a heating zone and back to saidchemicals coker.

(References on the following page) References Cited in the file of thispatent UNITED STATES PATENTS Blanding Mar. 5, 1946 Weikart Mar. 6, 1951Huff Nov. 6, 1951 Rex Aug. 26, 1952 8 Mattox Jan. 25, 1955 Kimberlin eta1. Oct. 18, 1955 Molstedt et a1 Feb. 21, 1956 Boston et a1 Feb. 21,1956 Burnside et a1. Feb; 28, 1956 Russell Apr. 10, 1956

1. A FLUIDIZED SOLIDS PETROLEUM RESIDUA COKING PROCESS FOR CONVERTINGCHARGE STOCK TO FUELS PRODUCTS AND CHEMICAL UNSATURATES WHICH COMPRISES,IN COMBINATION, COOKING A CHARGING STOCK IN A FLUID BED FUELS COKINGZONE WHILE MAINTAINING A RELATIVELY LOW SOLIDS RESIDENCE TIME WHEREBYONLY A PORTION OF THE CHARGING STOCK IS CONVERTED TO GASIFORM PRODUCTS,WITHDRAWING SOLIDS AND UNCONVERTED CHARGING STOCK FROM THE FLUID BED,HEATING THE WITHDRAWN PORTION TO A TEMPERATURE ABOVE 1200*F. BY ADDINGADDITIONAL HIGH TEMPERATURE SOLIDS, PASSING THE HEATED PORTION THROUGH ATRAANSFER LINE REACTOR TO CONVERT THE REMAINING PORTIONS OF SAIDCHARGING STOCK TO COKE AND LIGHT UNSATURATES WHILE MAINTAINING ANAVERAGE VAPOR RESIDENCE TIME OF LESS THAN 10 SECONDS IN SAID TRANSFERLINE REACTOR, AND SEPARATING AND RECOVERING THE CONVERSION PRODUCTS FROMEACH ZONE FROM THE CONTACT SOLIDS THEREIN.